0

In QGIS, I have a mountain range with a valley on either side (DEM raster file). Is there software or a plugin that allows me to calculate the easiest pathway over the mountain? The answers at Cost Distance Analyst In QGIS? are from 3 years ago and involves skills I've not yet acquired. Has nothing been developed in 3 years for us novices? Does QGIS3 not yet offer anything?

IanGS
  • 316
  • 1
  • 12
  • 8
    This is known as a Least Cost Path analysis, these questions have more details: Cost Distance Analyst In QGIS?, Least cost path between various points QGIS – Dan C Dec 04 '18 at 20:15
  • The answers at Cost Distance Analyst In QGIS? are from 3 years ago and involves skills I've not yet acquired. Has nothing been developed in 3 years for us novices? Does QGIS3 not yet offer anything? – IanGS Dec 07 '18 at 10:53
  • 1
    The tools in the answers to those questions are in QGIS3 and still work fine as far as I know. Have you tried them and found differently? Most algorithms used in GIS are much older than 3 years. Here's a tutorial on the SAGA tool, which is available in QGIS3. – Dan C Dec 07 '18 at 13:40
  • I'm sorry to say that I am finding it almost impossible to follow the process when all the previous 'answers' intertwine terminology/theory/names from GRASS, QGIS, ARCGIS, SAGA, etc. The best example of a clear demonstration is here https://www.youtube.com/watch?v=d0Eywj4pIu8 which is in ARCGIS, which of course I do not have. Am I correct in saying I need (1) DEM file, (2) Start Layer, (3) End Layer, and that I need to carry out the production of a (4) Cost Surface layer- the slope analysis, then a (5) Cost Distance layer, then a (6) Back Link layer, and then you can produce the (7) LCA layer? – IanGS Dec 15 '18 at 20:26
  • 1
    I haven't done this in a while but yes, the only inputs you would need if you are only concerned with elevation are the DEM and your start and end points. The rest is generated with the various tools. The tricky part is determining what your costs will be (the DEM is one) and their weights. As the narrator of that video points out, you can't hike across a lake, so to be more thorough you'd want to include a water layer as part of your costs. There may be vegetated areas which are tougher to walk through than steep slopes, so you may want to include those. It can get complicated. – Dan C Dec 16 '18 at 16:01
  • Thanks Dan. That was helpful. For my purposes (and especially for my learning curve) I am only interested in the cost of passing over the elevation (DEM layer). So do I now need a (1) Cost Surface layer- the slope analysis, then a (2) Cost Distance layer, then a (3) Back Link layer, and then I can produce the (4) LCA layer? If I can resolve this process I can begin to identify likely tools from the various toolboxes. – IanGS Dec 16 '18 at 18:21
  • In the 'answer' at https://gis.stackexchange.com/questions/140560/cost-distance-analyst-in-qgis it was suggested: "There are number of tools from GRASS and SAGA which allows for cost analysis which you can access from the Processing Toolbox:" The question is - which tools does one need for which tasks? (As a Newbie) – IanGS Dec 16 '18 at 18:44

0 Answers0